1. Field of the Invention
The present invention relates to a sheet feeding apparatus which feeds a sheet stacked on a sheet stacking portion to an image forming portion and an image forming apparatus including the same.
2. Description of the Related Art
Some of conventional image forming apparatuses such as a printer, a copying machine, and a facsimile include a sheet feeding apparatus which feeds a sheet to an image forming portion. Such a sheet feeding apparatus is configured to stack a sheet on a sheet stacking table arranged in a storing portion to enable lifting and lowering, lift the sheet stacking table to a position enabling sheet feeding, and thereafter send the sheet toward the image forming portion by a feeding roller.
For example, the sheet feeding apparatus is provided with a sheet surface detecting sensor which detects a height position of an uppermost sheet stacked on the sheet stacking table. This sheet surface detecting sensor is OFF when the uppermost sheet is at a height position enabling feeding and ON when the uppermost sheet is lower than the height position enabling feeding, for example.
When the sheet surface detecting sensor is ON, a controller is configured to drive a motor, e.g., to rotate a reel drum, and reel a wire attached to the sheet stacking table. This causes the sheet stacking table to lift, and when the uppermost sheet reaches the height position enabling feeding, the sheet surface detecting sensor is OFF to stop driving, and the sheet stacking table stops. This operation is repeated during sheet feeding to maintain the uppermost sheet at the height position enabling sheet feeding.
A recent requirement for improvement in efficiency of physical distribution promotes reduction in size and weight of packing materials, which brings about a tendency toward an increase in vibration and impact applied to an apparatus main body at the time of transporting the image forming apparatus including the sheet feeding apparatus. Thus, the sheet stacking table of the sheet feeding apparatus may be vibrated and damaged, and the sheet stacking table may collide with the feeding roller which feeds a sheet and break the roller portion.
To deal with this, a configuration is proposed in the sheet feeding apparatus, in which a lock member for transportation is provided to lock the sheet stacking table to prevent scratches and breakage caused by vibration and impact at the time of transportation. This sheet feeding apparatus has a lift hole vertically penetrating the sheet stacking table provided to be vertically movable on an accommodating surface accommodating a sheet and has a locking hole penetrating the lift hole and an opposed part on the accommodating surface when a lift plate is located along the accommodating surface. At the time of transportation, a stopper as the lock member is engaged with the lift hole and the locking hole, and a supporting plate of the stopper presses the sheet stacking table to prevent the sheet stacking table from moving upward from the accommodating surface and regulates unnecessary movement of the sheet stacking table (refer to Japanese Patent Laid-Open No. 2007-197204).
However, in a case of using the lock member for transportation, the lock member needs to be attached at the time of assembly and inevitably needs to be detached before use by a user. In this case, an attaching and detaching work of the lock member is required and is troublesome. In addition, in a case where detachment of the lock member is omitted before use, the sheet stacking table is lifted in a state where the lock member is attached, which may cause scratching and breakage of the sheet stacking table and peripheral members.
The present invention provides a sheet feeding apparatus which enables simple and reliable locking of a sheet stacking portion at the time of transportation and which enables extremely simple unlocking at the time of use and an image forming apparatus including the same.